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	$211.50	3.655%	$219.2303	$219.23	$219.25	$219.20
Purchase #2	$37.55	12.672%	$42.3083	$42.31	$42.30	$42.30
Purchase #3	$6.75	6.336%	$7.1777	$7.18	$7.20	$7.20
Purchase #4	$23.78	7.447%	$25.5509	$25.55	$25.55	$25.60
Purchase #5	$170.37	10.737%	$188.6626	$188.66	$188.65	$188.70
Purchase #6	$193.84	11.456%	$216.0463	$216.05	$216.05	$216.00
Purchase #7	$179.51	9.354%	$196.3014	$196.30	$196.30	$196.30
7 purchase totals =	$823.30		$895.2775	$895.28	$895.30	$895.30