Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$188.85	13.349%	$214.0596	$214.06	$214.05	$214.10
Purchase #2	$202.38	4.538%	$211.564	$211.56	$211.55	$211.60
Purchase #3	$195.48	10.652%	$216.3025	$216.30	$216.30	$216.30
Purchase #4	$179.90	3.197%	$185.6514	$185.65	$185.65	$185.70
Purchase #5	$136.37	7.348%	$146.3905	$146.39	$146.40	$146.40
Purchase #6	$172.58	13.775%	$196.3529	$196.35	$196.35	$196.40
Purchase #7	$127.88	3.103%	$131.8481	$131.85	$131.85	$131.80
7 purchase totals =	$1,203.44		$1,302.1690	$1,302.16	$1,302.15	$1,302.30