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	$196.59	4.601%	$205.6351	$205.64	$205.65	$205.60
Purchase #2	$242.56	3.112%	$250.1085	$250.11	$250.10	$250.10
Purchase #3	$67.82	3.466%	$70.1706	$70.17	$70.15	$70.20
Purchase #4	$146.53	6.505%	$156.0618	$156.06	$156.05	$156.10
Purchase #5	$86.68	12.484%	$97.5011	$97.50	$97.50	$97.50
Purchase #6	$192.91	3.719%	$200.0843	$200.08	$200.10	$200.10
Purchase #7	$223.48	9.145%	$243.9172	$243.92	$243.90	$243.90
7 purchase totals =	$1,156.57		$1,223.4786	$1,223.48	$1,223.45	$1,223.50