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	$153.56	11.854%	$171.763	$171.76	$171.75	$171.80
Purchase #2	$139.66	5.550%	$147.4111	$147.41	$147.40	$147.40
Purchase #3	$178.48	11.699%	$199.3604	$199.36	$199.35	$199.40
Purchase #4	$224.27	8.500%	$243.333	$243.33	$243.35	$243.30
Purchase #5	$53.72	3.557%	$55.6308	$55.63	$55.65	$55.60
Purchase #6	$196.60	7.469%	$211.2841	$211.28	$211.30	$211.30
Purchase #7	$162.41	3.192%	$167.5941	$167.59	$167.60	$167.60
7 purchase totals =	$1,108.70		$1,196.3765	$1,196.36	$1,196.40	$1,196.40