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	$65.58	10.154%	$72.239	$72.24	$72.25	$72.20
Purchase #2	$83.86	8.275%	$90.7994	$90.80	$90.80	$90.80
Purchase #3	$179.39	5.132%	$188.5963	$188.60	$188.60	$188.60
Purchase #4	$6.53	5.543%	$6.892	$6.89	$6.90	$6.90
Purchase #5	$161.62	3.349%	$167.0327	$167.03	$167.05	$167.00
Purchase #6	$32.96	12.612%	$37.1169	$37.12	$37.10	$37.10
Purchase #7	$163.52	4.615%	$171.0664	$171.07	$171.05	$171.10
7 purchase totals =	$693.46		$733.7427	$733.75	$733.75	$733.70