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	$114.41	11.764%	$127.8692	$127.87	$127.85	$127.90
Purchase #2	$224.30	3.595%	$232.3636	$232.36	$232.35	$232.40
Purchase #3	$55.69	12.584%	$62.698	$62.70	$62.70	$62.70
Purchase #4	$229.82	12.402%	$258.3223	$258.32	$258.30	$258.30
Purchase #5	$84.81	4.793%	$88.8749	$88.87	$88.85	$88.90
Purchase #6	$223.46	3.755%	$231.8509	$231.85	$231.85	$231.90
Purchase #7	$39.70	10.459%	$43.8522	$43.85	$43.85	$43.90
7 purchase totals =	$972.19		$1,045.8311	$1,045.82	$1,045.75	$1,046.00