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	$127.28	3.472%	$131.6992	$131.70	$131.70	$131.70
Purchase #2	$80.40	7.600%	$86.5104	$86.51	$86.50	$86.50
Purchase #3	$27.74	5.674%	$29.314	$29.31	$29.30	$29.30
Purchase #4	$211.93	3.516%	$219.3815	$219.38	$219.40	$219.40
Purchase #5	$159.50	7.467%	$171.4099	$171.41	$171.40	$171.40
Purchase #6	$155.38	4.535%	$162.4265	$162.43	$162.45	$162.40
Purchase #7	$45.55	4.867%	$47.7669	$47.77	$47.75	$47.80
7 purchase totals =	$807.78		$848.5084	$848.51	$848.50	$848.50