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	$124.79	5.498%	$131.651	$131.65	$131.65	$131.70
Purchase #2	$79.59	11.117%	$88.438	$88.44	$88.45	$88.40
Purchase #3	$110.65	7.497%	$118.9454	$118.95	$118.95	$118.90
Purchase #4	$138.96	8.257%	$150.4339	$150.43	$150.45	$150.40
Purchase #5	$42.77	6.435%	$45.5222	$45.52	$45.50	$45.50
Purchase #6	$45.49	5.251%	$47.8787	$47.88	$47.90	$47.90
Purchase #7	$114.98	4.587%	$120.2541	$120.25	$120.25	$120.30
7 purchase totals =	$657.23		$703.1233	$703.12	$703.15	$703.10