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	$197.60	10.689%	$218.7215	$218.72	$218.70	$218.70
Purchase #2	$222.40	11.170%	$247.2421	$247.24	$247.25	$247.20
Purchase #3	$72.41	9.525%	$79.3071	$79.31	$79.30	$79.30
Purchase #4	$179.81	9.284%	$196.5036	$196.50	$196.50	$196.50
Purchase #5	$121.29	10.365%	$133.8617	$133.86	$133.85	$133.90
Purchase #6	$33.85	9.484%	$37.0603	$37.06	$37.05	$37.10
Purchase #7	$127.95	13.664%	$145.4331	$145.43	$145.45	$145.40
7 purchase totals =	$955.31		$1,058.1294	$1,058.12	$1,058.10	$1,058.10