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	$104.72	7.847%	$112.9374	$112.94	$112.95	$112.90
Purchase #2	$39.83	5.733%	$42.1135	$42.11	$42.10	$42.10
Purchase #3	$241.40	5.407%	$254.4525	$254.45	$254.45	$254.50
Purchase #4	$80.93	8.191%	$87.559	$87.56	$87.55	$87.60
Purchase #5	$25.56	7.232%	$27.4085	$27.41	$27.40	$27.40
Purchase #6	$154.26	6.518%	$164.3147	$164.31	$164.30	$164.30
Purchase #7	$60.31	6.721%	$64.3634	$64.36	$64.35	$64.40
7 purchase totals =	$707.01		$753.1490	$753.14	$753.10	$753.20