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	$142.37	13.873%	$162.121	$162.12	$162.10	$162.10
Purchase #2	$96.34	13.218%	$109.0742	$109.07	$109.05	$109.10
Purchase #3	$42.97	8.308%	$46.5399	$46.54	$46.55	$46.50
Purchase #4	$175.59	12.204%	$197.019	$197.02	$197.00	$197.00
Purchase #5	$134.51	3.734%	$139.5326	$139.53	$139.55	$139.50
Purchase #6	$189.55	13.427%	$215.0009	$215.00	$215.00	$215.00
Purchase #7	$174.93	9.613%	$191.746	$191.75	$191.75	$191.70
7 purchase totals =	$956.26		$1,061.0336	$1,061.03	$1,061.00	$1,060.90