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	$223.38	10.411%	$246.6361	$246.64	$246.65	$246.60
Purchase #2	$200.26	10.148%	$220.5824	$220.58	$220.60	$220.60
Purchase #3	$145.59	9.377%	$159.242	$159.24	$159.25	$159.20
Purchase #4	$164.84	5.624%	$174.1106	$174.11	$174.10	$174.10
Purchase #5	$141.52	7.377%	$151.9599	$151.96	$151.95	$152.00
Purchase #6	$218.54	5.763%	$231.1345	$231.13	$231.15	$231.10
Purchase #7	$12.59	5.535%	$13.2869	$13.29	$13.30	$13.30
7 purchase totals =	$1,106.72		$1,196.9524	$1,196.95	$1,197.00	$1,196.90