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	$187.83	4.411%	$196.1152	$196.12	$196.10	$196.10
Purchase #2	$53.76	5.530%	$56.7329	$56.73	$56.75	$56.70
Purchase #3	$167.60	11.757%	$187.3047	$187.30	$187.30	$187.30
Purchase #4	$242.27	11.424%	$269.9469	$269.95	$269.95	$269.90
Purchase #5	$236.68	7.372%	$254.128	$254.13	$254.15	$254.10
Purchase #6	$156.48	3.695%	$162.2619	$162.26	$162.25	$162.30
Purchase #7	$96.92	4.582%	$101.3609	$101.36	$101.35	$101.40
7 purchase totals =	$1,141.54		$1,227.8505	$1,227.85	$1,227.85	$1,227.80