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	$242.85	4.632%	$254.0988	$254.10	$254.10	$254.10
Purchase #2	$197.74	9.261%	$216.0527	$216.05	$216.05	$216.10
Purchase #3	$45.84	4.534%	$47.9184	$47.92	$47.90	$47.90
Purchase #4	$112.30	8.765%	$122.1431	$122.14	$122.15	$122.10
Purchase #5	$96.50	4.328%	$100.6765	$100.68	$100.70	$100.70
Purchase #6	$247.69	3.118%	$255.413	$255.41	$255.40	$255.40
Purchase #7	$157.98	6.496%	$168.2424	$168.24	$168.25	$168.20
7 purchase totals =	$1,100.90		$1,164.5449	$1,164.54	$1,164.55	$1,164.50