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	$156.89	7.735%	$169.0254	$169.03	$169.05	$169.00
Purchase #2	$174.69	12.476%	$196.4843	$196.48	$196.50	$196.50
Purchase #3	$100.80	11.830%	$112.7246	$112.72	$112.70	$112.70
Purchase #4	$182.67	5.292%	$192.3369	$192.34	$192.35	$192.30
Purchase #5	$46.25	6.587%	$49.2965	$49.30	$49.30	$49.30
Purchase #6	$250.25	3.708%	$259.5293	$259.53	$259.55	$259.50
Purchase #7	$37.63	13.303%	$42.6359	$42.64	$42.65	$42.60
7 purchase totals =	$949.18		$1,022.0329	$1,022.04	$1,022.10	$1,021.90